This invention relates to an electronic timepiece comprising an electric power supply source, a piezoelectric resonator, display means for time indications and electronic circuits in the form of an integrated circuit which comprises an oscillator associated to the resonator, a frequency divider, means for performing at least one auxiliary function in dependence on an information being present at inputs thereof and a control circuit for the display means, said integrated circuit having a first group of m terminals whereof k are intended to connect said source with said electronic circuits and (m-k) to connect, at least indirectly, at least part of said control circuit for the display with at least part of said display means.
Most of the known electronic timepiece utilize quartz crystal oscillators as a time base. Such oscillators deliver pulses at a relatively high and very stable frequency of e.g. 32 kHz, to a frequency divider which is connected to the control circuit for the time display.
The operations required for precise frequency setting of the quartz crystal are time consuming and delicate and they are an important factor contributing to the increase of the price of such an element.
Different systems have been proposed to allow the utilization of quartz crystals which have not undergone such operations of frequency setting, which means that these quartz crystals have a natural frequency which is different from the theoretically necessary frequency.
Some of such systems, working with quartz crystals whose frequency is lower than the theoretical frequency, are provided with a frequency divider of which the dividing ratio may be decreased, or with a special circuit which adds, at given moments, correcting pulses to the input of one or more stages of the divider, so that the frequency of the signals delivered at the output of the divider becomes equal to the desired frequency.
Other systems, which are working with quartz crystals whose frequency is higher than the theoretical frequency, are arranged for suppressing a certain number of pulses at the input of the divider at predetermined time intervals.
Whatever the system is, the watches equipped therewith must be provided with means permitting at least the introduction and in certain cases the memorization of the information needed by the adjustment circuit so that the latter will be able to act on the divider circuit in such a way as to obtain at its output signals of the desired frequency.
One of the simplest means known to introduce the information needed by the adjustment circuit makes use of terminals of the integrated circuit which comprises all electronic circuits of the watch. Such terminals are intended and reserved for that purpose and they can be connected by switches, screws, soldered or glued bridges or the like to one or to the other pole of the electric power supply source which is generally a battery or an accumulator. A connection with the negative pole of the source means e.g. a logic state 0 and a connection with the positive pole a logic state 1. The terminals are simply connected to the inputs of the circuit for the adjustment of the frequency and the information of correction is given by the combination of the logic states 0 and 1 of the terminals.
By using such a simple system, it is possible with n terminals to introduce 2.sup.n distinctive information. In order to introduce e.g. 64 information, 6 terminals must be provided. Now, it is known that the terminals of an integrated circuit are a possible source of failure because of the way they open to the humidity to penetrate into the circuit. The terminal contribute also to a considerable extent to the price of the integrated circuit. It is therefore desirable to limit their number as far as possible.